Disposable absorbent article having improved in-use storage capacity for low and medium low viscosity feces

ABSTRACT

A disposable absorbent article, such as a diaper, comprising a medium viscosity feces storage material having an improved ability to store in particular medium low viscosity feces.

FIELD OF THE INVENTION

This invention relates to disposable absorbent articles, such as diapersand adult incontinence products, and more particularly to disposableabsorbent articles which have the capacity to retain low and medium-lowviscosity feces and thus keep these away from the skin of the wearer, inorder to reduce leakage and make it easier to clean the wearer when thesoiled disposable absorbent article is removed.

BACKGROUND OF THE INVENTION

Disposable absorbent articles such as diapers and adult incontinenceproducts are well known in the art. Such disposable absorbent articlescollect and retain urine and feces deposited thereon by the wearer.While a great deal of effort has been and still is spent againstimproving the handling of urine, relatively little has been done toimprove the handling of feces, in particular when dealing with low ormedium viscosity feces.

Feces can be discharged by the wearer over a wide range of amounts,number of occurrences, consistency, depending on the age (newborn toadults) or condition of the wearer (nutrition, sicknesses, etc.). It issaid, that daily loadings can average between 100 gram to over 1000 gunder pathologic conditions, with individual daily loadings being as lowa 40 grams. The loading frequency is generally higher with small babies(newborn up to five occurrences per day), and decreasing with age toabout once per day for adults. Composition is also very variable, butwithin the scope of the present invention the amount of water is ofparticular interest, which can range from about 70% to about 90% oftotal discharge. Correspondingly, the consistency of such discharges(often referred to a as “bowel movements” or abbreviated “BM”) can rangefrom “firm” over “pasty” to “runny”. Within the scope of the presentinvention, this consistency can best be correlated with the technicalmeasure of viscosity.

Obviously, the handling of such materials requires very differentstructures as compared to the structures for “storage” or absorbency offluids like urine. For the latter, a much smaller pore sizes is required(which can be even as small as to molecular size, such as provided by“superabsorbent materials”, though there in addition to other effects).Storage of feces however, requires sufficiently open/large pores forbeing able to receive the feces, which—in comparison to urine—have amuch higher viscosity. This requirement applies both to the topsheet(facing) materials of an absorbent article, and also to materials whichare supposed to store respective materials.

Attempts to improve the handling of feces include providing a firsttopsheet which conforms closely to the wearer and has an aperture. Theaperture is hopefully registered with the anal opening, so that fecespasses there through into a void space. The first topsheet may comprisevarious elastic panels in order to closely conform to the skin of thewearer, and/or may have linear elastic strands. Improvements have beenmade in this area of the prior art, such as optimizing the materialproperties of the first topsheet. Such optimization makes the firsttopsheet more comfortable to the wearer and allows a single disposableabsorbent article to fit a larger range of sizes of wearers. Examplesfor such approaches are given in EP-A-0 359 410; EP-A-0 386 816; EP-A-0644 747.

Further improvements to this type of the prior art disposable absorbentarticles also include the addition of spacers. Spacers may be interposedbetween the first topsheet and the core, in order to ensure a void spaceis present to receive the feces. Examples for these approaches are givenin U.S. Pat. No. 4,778,459; FR-2 495 899; WO 90/14063; WO 93/12748.

Yet other attempts have been made for such types of the prior artarticles by providing barriers which limit the movement of feces toparticular portions of the disposable absorbent article. The barrierslimit the contact of the feces to a lesser portion of the skin of thewearer, than a comparable disposable absorbent article which has nobarriers. Such approaches are disclosed in U.S. Pat. No. 5,514,121;EP-A-0 486 006.

However, none of these attempts to handle feces solve the specificproblems which occur when feces of a softer consistency is present, suchas being prevalent for younger children, particularly those who arebreast fed. Such lower viscosity feces are referred to by mothers as“runny bowel movement (or BM)” corresponding to low-viscosity feces, or“pasty BM” for feces of a higher consistency, which however still has amuch lower viscosity than “firm BM”. Such lower viscosity feces easilymigrate within the disposable absorbent article under the influences ofgravity and motion or pressure by the wearer.

The migration of the feces often results in movement of it on thesurface of the absorbent article towards the perimeter of the disposableabsorbent article, increasing the likelihood of leakage. The migrationof the feces also smears it against the skin of the wearer, makingcleanup more difficult. In order to clean the wearer, the caretaker mustwipe the entire area of the skin which has encountered the feces andtypically has to deal with a relatively large soiled area.

One serious attempt in the art to handle low-viscosity feces is found inU.S. Pat. No. 5,342,338. This application describes a disposableabsorbent article having a first topsheet with a high trans-topsheetpenetration overlaying a secondary topsheet having a lessertrans-topsheet penetration.

PCT US 94/08958 discloses further a disposable absorbent article whichreduces leakage of low-viscosity feces from the disposable absorbentarticle and aims at minimizing the amount of low-viscosity fecesremaining on the skin of the wearer once the disposable absorbentarticle is removed by combining a topsheet with high trans-topsheetpenetration and a fecal storage material.

However, the prior art referred to herein before is relying on in-usemovements to create storage space, such as by allowing the topsheet todetach from the underlying fluid storage structure possibly enhanced byelastic features. Hence it is an object of the current invention, toprovide such storage space from the beginning of the use period and tofurther maintain such storage space during use.

Hence it is an object of the invention to provide structures withimproved feces handling properties especially for medium viscosityfeces, as expressed by improved feces storage capacity.

It is a further object of the invention to allow selection of theappropriate materials for such improved structures by assessing themedium viscosity feces storage capacity, related to either the amount ofmaterial used or the area of the material.

BRIEF SUMMARY OF THE INVENTION

A disposable absorbent article, such as a diaper, comprising a mediumviscosity feces storage material having an improved ability to store inparticular medium low viscosity feces. Such storage materials arecharacterized in having a feces storage capacity of at least 20 g/g,preferably of more than 35 g/g, when tested according to the describedtest for medium viscosity fecal storage capacity.

BRIEF DESCRIPTION OF THE DRAWINGS

While the Specification concludes with claims pointing out anddistinctly claiming the present invention, it is believed the same willbe better understood by the following drawings taken in conjunction withthe accompanying Specification wherein like components are given thesame reference number and:

FIGS. 1a and b are a top plan view, shown partially in cutaway, ofdisposable absorbent article according to the present invention with twodifferent arrangements of the absorbent core and the storage material;

FIGS. 2a and b are a vertical sectional view taken along thecross-directional lines 2—2 of FIGS. 1a and b, showing the relationshipof the first topsheet, feces storage material and absorbent core;

FIGS. 3a and b are a vertical sectional view taken alongmachine-directional lines 3—3 of FIGS. 1a and b, showing therelationship of the first topsheet, feces storage material and absorbentcore;

FIG. 4 is a schematic side view of an apparatus which may be used tomeasure the capacity of the disposable absorbent article;

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “absorbent article” refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain the various exudates discharged from thebody. The term “disposable” is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise disposed of in an environmentally compatible manner). Apreferred embodiment of an absorbent article of the present invention isthe disposable absorbent article, diaper 20, shown in FIG. 1. As usedherein, the term “diaper” refers to an absorbent article generally wornby infants and adult incontinent persons and is worn about the lowertorso of the wearer.

FIG. 1 is a plan view of the diaper 20 of the present invention in itsflat-out, uncontracted state (i.e., with elastic induced contractionpulled out) with portions of the structure being cut-away to moreclearly show the construction of the diaper 20 and with the portion ofthe diaper 20 which faces or contacts the wearer, the inner surface,oriented towards the viewer. As shown in FIG. 1, the diaper 20preferably comprises a liquid pervious first topsheet 24; a liquidimpervious backsheet 26 joined with the first topsheet 24; a liquidpervious feces storage material 25 intermediate the first topsheet 24and the backsheet 26; and optionally an absorbent core 28 intermediatethe feces storage material 25 and the backsheet 26. This absorbent core28 is generally intended and designed to absorb urine and can, ofcourse, also pick up certain amounts of the feces, such as aqueousportions. Thus, the feces storage material 25 can be a separatecomponent than absorbent core 28, or integral with absorbent core 28, ora combination thereof. The diaper 20 may further comprise elasticizedside panels (not shown); elasticized leg cuffs (not shown); an elasticwaist feature (not shown); and a fastening system with tape tabs—(notshown)—.

The diaper 20 is shown in FIG. 1 to have a first waist region 27juxtaposed with the front of the wearer while the diaper 20 is beingworn, a second waist region 29 opposed to the first waist region 27 andjuxtaposed with the back of the wearer while the diaper 20 is beingworn, a crotch region 31 positioned between the first waist region 27and the second waist region 29, and a periphery which is defined by theouter edges of the diaper 20 in which the longitudinal edges aredesignated 33 and the end edges are designated 35. The inner surface ofthe diaper 20 comprises that portion of the diaper 20 which is adjacentto the wearer's body during use (i.e., the inner surface generally isformed by at least a portion of the first topsheet 24 and othercomponents joined to the first topsheet 24). The outer surface comprisesthat portion of the diaper 20 which is positioned away from the wearersbody (i.e., the outer surface generally is formed by at least a portionof the backsheet 26 and other components joined to the backsheet 26)during use.

FIG. 2 shows an embodiment of the diaper 20 in which the first topsheet24 and the backsheet 26 have length and width dimensions generallylarger than those of the absorbent core 28. The first topsheet 24 andthe backsheet 26 extend beyond the edges of the absorbent core 28 tothereby form the periphery of the diaper 20. Alternatively, the fecesstorage material 25 may, but need not, extend beyond the edges of theabsorbent core 28 and be joined to the backsheet 26 to form theperiphery of the diaper 20 and the first topsheet 24 smaller than orcoextensive of the core 28. While the first topsheet 24, the fecesstorage material 25, the backsheet 26, and the core 28 may be assembledin a variety of well known configurations, preferred diaperconfigurations are described generally in U.S. Pat. No. 3,860,003entitled “Contractable Side Portions for Disposable Diaper” which issuedto Kenneth B. Buell on Jan. 14, 1975; and U.S. Pat. No. 5,151,092,“Absorbent Article With Dynamic Elastic Waist Feature Having APredisposed Resilient Flexural Hinge”, issued to Kenneth B. Buell et al.Sep. 29, 1992.

The absorbent core 28 may be any absorbent means which is generallycompressible, conformable, non-irritating to the wearer's skin, andcapable of absorbing and retaining liquids such as urine. As shown inFIG. 1, the absorbent core 28 has a garment surface, a body surface,side edges, and waist edges. The absorbent core 28 may be manufacturedin a wide variety of sizes and shapes (e.g., rectangular, hourglass,“T”-shaped, asymmetric, etc.) and from a wide variety ofliquid-absorbent materials commonly used in disposable diapers and otherabsorbent articles such as comminuted wood pulp which is generallyreferred to as airfelt. Examples of other suitable absorbent materialsinclude creped cellulose wadding; meltblown polymers including coform;chemically stiffened, modified or cross-linked cellulosic fibers; tissueincluding tissue wraps and tissue laminates; absorbent foams; absorbentsponges; superabsorbent polymers; absorbent gelling materials; or anyequivalent material or combinations of materials.

The configuration and construction of the absorbent core 28 may also bevaried (e.g., the absorbent core 28 may have varying caliper zones, ahydrophilic gradient, a superabsorbent gradient, or lower averagedensity and lower average basis weight acquisition zones; or maycomprise one or more layers or structures). The total absorbent capacityof the absorbent core 28 should, however, be compatible with the designloading and the intended use of the diaper 20. Further, the size andabsorbent capacity of the absorbent core 28 may be varied to accommodatewearers ranging from infants through adults.

Exemplary absorbent structures for use as the absorbent core 28 aredescribed in U.S. Pat. No. 4,610,678 entitled “High-Density AbsorbentStructures” issued to Weisman et al. on Sep. 9, 1986; U.S. Pat. No.4,673,402 entitled “Absorbent Articles With Dual-Layered Cores” issuedto Weisman et al. on Jun. 16, 1987; U.S. Pat. No. 4,888,231 entitled“Absorbent Core Having A Dusting Layer” issued to Angstadt on Dec. 19,1989; and U.S. Pat. No. 4,834,735, entitled “High Density AbsorbentMembers Having Lower Density and Lower Basis Weight Acquisition Zones”,issued to Alemany et al. on May 30, 1989.

The backsheet 26 is positioned adjacent the garment surface of theabsorbent core 28 and is preferably joined thereto by attachment means(not shown) such as those well known in the art. As used herein, theterm “joined” encompasses configurations whereby an element is directlysecured to the other element by affixing the element directly to theother element, and configurations whereby the element is indirectlysecured to the other element by affixing the element to intermediatemember(s) which in turn are affixed to the other element.

For example, the backsheet 26 may be secured to the absorbent core 28 bya uniform continuous layer of adhesive, a patterned layer of adhesive,or an array of separate lines, spirals, or spots of adhesive. Adhesiveswhich have been found to be satisfactory are manufactured by H.B. FullerCompany of St. Paul, Minn. and marketed as HL-1258. The attachment meanswill preferably comprise an open pattern network of filaments ofadhesive as is disclosed in U.S. Pat. No. 4,573,986 entitled “DisposableWaste-Containment Garment”, which issued to Minetola et al. on Mar. 4,1986, more preferably several lines of adhesive filaments swirled into aspiral pattern such as is illustrated by the apparatus and methods shownin U.S. Pat. No. 3,911,173 issued to Sprague, Jr. on Oct. 7, 1975; U.S.Pat. No. 4,785,996 issued to Ziecker, et al. on Nov. 22, 1978; and U.S.Pat. No. 4,842,666 issued to Werenicz on Jun. 27, 1989. Alternatively,the attachment means may comprise heat bonds, pressure bonds, ultrasonicbonds, dynamic mechanical bonds, or any other suitable attachment meansor combinations of these attachment means as are known in the art.

The backsheet 26 is impervious to fluids like urine or feces, and ispreferably manufactured from a thin plastic film, although otherflexible liquid impervious materials may also be used. As used herein,the term “flexible” refers to materials which are compliant and willreadily conform to the general shape and contours of the human body.

The backsheet 26 prevents the exudates absorbed and contained in theabsorbent core 28 from wetting articles which contact the diaper 20 suchas bedsheets and undergarments. The backsheet 26 may thus comprise awoven or nonwoven material, polymeric films such as thermoplastic filmsof polyethylene or polypropylene, or composite materials such as afilm-coated nonwoven material. Preferably, the backsheet 26 is athermoplastic film having a thickness of about 0.012 mm (0.5 mil) toabout 0.051 mm (2.0 mils). Particularly preferred materials for thebacksheet 26 include RR8220 blown films and RR5475 cast films asmanufactured by Tredegar Industries, Inc. of Terre Haute, Ind. Thebacksheet 26 is preferably embossed and/or matte finished to provide amore clothlike appearance. Further, the backsheet 26 may permit vaporsto escape from the absorbent core 28 (i.e., be breathable) while stillpreventing exudates from passing through the backsheet 26.

The diaper 20 may further comprise elasticized leg cuffs (not shown)which provide improved containment of liquids and other body exudates.Each elasticized leg cuff may comprise several different embodiments forreducing the leakage of body exudates in the leg regions. (The leg cuffcan be and is sometimes also referred to as leg bands, side flaps,barrier cuffs, or elastic cuffs.) U.S. Pat. No. 3,860,003 describes adisposable diaper 20 which provides a contractible leg opening having aside flap and one or more elastic members to provide an elasticized legcuff (gasketing cuff). Commonly assigned U.S. Pat. No. 4,909,803entitled “Disposable Absorbent Article Having Elasticised Flaps” issuedto Aziz et al. on Mar. 20, 1990, describes a disposable diaper 20 having“stand-up” elasticized flaps (barrier cuffs) to improve the containmentof the leg regions. Commonly assigned U.S. Pat. No. 4,695,278 entitled“Absorbent Article Having Dual Cuffs” issued to Lawson on Sep. 22, 1987,describes a disposable diaper 20 having dual cuffs including a gasketingcuff and a barrier cuff.

The diaper 20 preferably further comprises an elastic waist feature (notshown) that provides improved fit and containment. The elastic waistfeature is that portion or zone of the diaper 20 which is intended toelastically expand and contract to dynamically fit the wearer's waist.The elastic waist feature at least extends longitudinally outwardly fromat least one of the waist edges of the absorbent core 28 and generallyforms at least a portion of the end edge of the diaper 20. Disposablediapers are generally constructed so as to have two elastic waistfeatures, one positioned in the first waist region 27 and one positionedin the second waist region 29, although diapers can be constructed witha single elastic waist feature. Further, while the elastic waist featureor any of its constituent elements can comprise a separate elementaffixed to the diaper 20, the elastic waist feature is preferablyconstructed as an extension of other elements of the diaper 20 such asthe backsheet 26 or the first topsheet 24, preferably both the backsheet26 and the first topsheet 24. The elasticized waistband 34 may beconstructed in a number of different configurations including thosedescribed in U.S. Pat. No. 4,515,595 issued to Kievit et al. on May 7,1985 and the above referenced U.S. patent application Ser. No.07/715,152.

The diaper 20 also comprises a fastening system 36 which forms a sideclosure which maintains the first waist region 27 and the second waistregion 29 in an overlapping configuration such that lateral tensions aremaintained around the circumference of the diaper 20 to maintain thediaper 20 on the wearer. Exemplary fastening systems are disclosed inU.S. Pat. No. 4,846,815 entitled “Disposable Diaper Having An ImprovedFastening Device” issued to Scripps on Jul. 11, 1989; U.S. Pat. No.4,894,060 entitled “Disposable Diaper With Improved Hook FastenerPortion” issued to Nestegard on Jan. 16, 1990; commonly assigned U.S.Pat. No. 4,946,527 entitled “Pressure-Sensitive Adhesive Fastener AndMethod of Making Same” issued to Battrell on Aug. 7, 1990; commonlyassigned U.S. Pat. No. 3,848,594 entitled “Tape Fastening System forDisposable Diaper” issued to Buell on Nov. 19, 1974; commonly assignedB1 U.S. Pat. No. 4,662,875 entitled “Absorbent Article” issued toHirotsu et al. on May 5, 1987; and the herein before referenced U.S.patent application Ser. No. 07/715,152.

The diaper 20 is preferably applied to a wearer by positioning one ofthe waist regions, preferably the second waist region 29, under thewearer's back and drawing the remainder of the diaper 20 between thewearer's legs so that the other waist region, preferably the first waistregion 27, is positioned across the front of the wearer. The tape tabs36 of the fastening system are then released from the release portion.The diaperer then wraps the elasticized side panel around the wearer,while still grasping the tab portion. The fastening system is secured tothe outer surface of the diaper 20 to effect two side closure.

The first topsheet 24 and the feces storage material 25 each have twomajor faces. The first topsheet 24 has a first major face orientedtowards the wearer and an opposed second major face oriented towards thefeces storage material 25. The feces storage material 25 has a firstmajor face oriented towards the first topsheet 24, and an opposed secondmajor face oriented towards the core 28, if it is separate from thefeces storage material 25.

The first topsheet 24 is juxtaposed with, but not necessarily adjacentthe body surface of the feces storage material 25, and is preferablyjoined to the backsheet 26 or feces storage material 25 by means such asthose well known in the art. Suitable attachment means are describedabove with respect to joining the backsheet 26 to the absorbent core 28.In a preferred embodiment of the present invention, the first topsheet24 and the backsheet 26 are joined directly to each other in the diaperperiphery.

The first topsheet 24 is compliant, soft feeling, and non-irritating tothe wearer's skin. Further, the first topsheet 24 is liquid pervious,permitting liquids (e.g., urine) to readily penetrate through itsthickness. A suitable first topsheet 24 may be manufactured from a widerange of materials, such as porous foams; reticulated foams; aperturedplastic films; or woven or nonwoven webs of natural fibers (e.g., woodor cotton fibers), synthetic fibers (e.g., polyester or polypropylenefibers), or a combination of natural and synthetic fibers. There are anumber of manufacturing techniques which may be used to manufacture thefirst topsheet 24. For example, the first topsheet 24 may be a nonwovenweb of fibers spunbonded, carded, wet-laid, meltblown, hydroentangled,combinations or composite laminates of the above, or the like. Furtheroptions for the first topsheets 24 include a carded/carded composite,hydroentangled over a wire forming screen and thermally air-throughbonded by means well known to those skilled in the nonwovens art andhydroentanglement of fibrous webs. Particularly preferred are aperturedformed films comprising a central layer of apertured films, beingcovered with non-woven material on both side, which also has aperturescoinciding with the arrangement of apertures of the film.

U.S. Pat. No. 5,342,338 has pointed to the importance of the “TransTopsheet capacity for low viscosity fecal material” (i.e. feces) asdescribed therein. Thereby, the diaper 20 should have a trans-topsheetcapacity of at least about 0.20 grams per square inch provided thediaper has at least 193 cm² (30 square inches) surface area. Aparticularly preferred execution related to an example whereby acombination of an apertured film/non-woven laminate (one example ofwhich is PANTEX 18125X) as a topsheet together with an apertured film(one example of which is TREDEGAR X5790).

However, these trans-topsheet capacities are not sufficient to allowoptimization of feces handling performance, in particular when alsohigher viscosity or higher consistency feces are considered. In theseinstances, not only the ease of penetrating through the element isrelevant, but also the storage capacity of the storage material itselfis relevant. Therefore, the trans-topsheet penetration test has beenmodified, such that now particularly useful materials could be screenedout.

This “medium viscosity feces storage capacity test” is made (understandard laboratory conditions of 23 degree Celsius and 50% relativehumidity) on a flat sample specimen of a size of 10 cm by 10 cm.

The material is covered by a perspex plate of same dimensions of 10 cmby 10 cm, and a thickness of 5 mm, having an hole of 3 cm diameter inthe center of the plate, whereon a circular perspex tube of an innerdiameter of also 3 cm is fixed. The height of this tube is 20 cm, and acylinder is positioned inside such that it can smoothly glide inside thetube. (The tightness of the fitting is such that the test fluid asdescribed below cannot be squeezed out under the applied pressure). Afurther part of the equipment is a weight to load the cylinder such thatat its lower area a pressure of 5171 Pa (0.75 psi) is applied, and afurther weight of 305 g to be placed on the perspex plate to submit thetest specimen to a pressure of 427 Pa (0.0608 psi).

In order to be able to asses the material properties with regard tohandling not only low viscosity materials, but also medium viscositymaterials, the test fluid applied in this specific test is an aqueoussolution of CARBOPOL ETD 2050, such as available from BF GoodrichChemical (Deutschland) GmbH, Neuss, Germany. A particularly usefulsolution contains a 0.5% of this polymer, having—after carefulpreparation according to the standard procedure as provided by saidsupplier—, a viscosity of about 16000 cps also as according to theprocedure given by said supplier for Brookfield viscometer.

For executing the test, the preweighed feces storage test specimen iscut to the desired size, and placed between (also preweighed) sheets ofthe same size of (i) a conventional polyethylene-film (such as used asbacksheet material in diapers) and (ii) a standardized topsheet. For thehigher viscosity materials an apertured film was particularly useful.Apertured film/nonwoven laminates are referred to and have been testedas supplied by Pantex S.A., Italy.

These are laminated composites, consisting of a layer of about 20 μmpolyethylene film between two layers of a conventional spunbonded web ofabout 14 g/m2, made of polypropylene fibers. The webs are essentially ashydrophobic as polypropylene.

The apertures are essentially rectangular holes of about 0.5 mm² sizepunched by heated embossing pattern roll through all three layers. Thereare about 40 apertures per cm, covering approximately 20% of totalsurface. The bonding is achieved through the process of aperturing,where some melting of fibers occurs around the holes. This material isalso disclosed in more detail in EP 0 207 904.

These sheets are carefully positioned and centered under the perspexplate. Then 20 g of test fluid is put into the tube, the cylinder iscarefully fit into the tube, and the weights are applied both to perspexplate and the cylinder.

After 10 minutes testing time, the perspex plate as is carefully removedsuch that no further test fluid is transferred to or retained by thesheets beyond what has been picked up during these 10 minutes, and allthree sheets are carefully weighted, whereby again care must be taken toseparate these sheets without transferring test fluid from one layer tothe other through that separation.

After weighing the test specimen, the area of the stain of test fluid inthe specimen is determined by conventional methods, such as by measuringthe diameter if sufficiently close to a circular distribution, or byusing conventional Computerized Image Analysis tools, possibly includingmanually transfer of the stain size to a transparency.

The direct reading at the end of the test is the amount of material aspicked up under the applied pressure during the testing time by thespecimen and the stain size. In order to allow better comparison betweenmaterials and designs, the material basis capacity and the materialcapacity are calculated.

First, the material basis capacity is calculated (in g/cm²) by dividingthe amount of material picked up by the test specimen (in gram) by thesize if the stain (cm²). This parameter can then be used to design thesize of the feces storage material.

The material capacity (in g/g) is the result of dividing the materialbasis capacity by the basis weight (in g/cm²), thus giving the amount offluid picked up per amount of material used. This parameter is importantfor designing material usages of the fecal storage materials.

Without wishing to be bound by the theory, is believed, that themechanism of medium viscosity feces pick up is still dominated bycapillary transport mechanisms, thus providing readily available storagespace. Hence, the porosity and its dependency on applied pressures isimportant. However, a careful balance has to be met to not compromisetoo much on the softness of the materials. In order to compare thematerials with regard to these properties, the materials were submittedto the resiliency test.

Thereby, samples were submitted in a conventional compression/pressureanalysis equipment such as an INSTRON tester, which allows a constantcrosshead speed of 10 mm per minute, and allow reading of crossheadposition at certain pressure readings. Most conveniently, this can beachieved by plotting the compression curve and the graphicallydetermining the calipers corresponding to a pressure of 1379 Pa, 2578Pa, 3448 Pa, 5516 Pa and 6895 Pa (0.2, 0.4, 0.5, 0.8, and 1.0 psi),respectively. After reaching the highest compression, the pressure wasreduced to 552 Pa (0.08 psi) for 5 seconds and the caliper was measuredagain. This cycle is repeated for three times, and the respectivereadings are averaged. The caliper readings then allow to calculate therespective thickness loss of the material at the given pressure, orafter the cycle.

Useful materials to be applied in the present invention are open fibrousstructures, and particularly useful materials are air laid, air throughbonded nonwoven, using eccentric, polyethylene sheath/polypropylene corebicomponent fibers with a permanent incorporated into the polyethyleneresin. Such webs provide open resilient fibrous structures, withoutcompromising on the softness.

EXAMPLES

In order to exemplify the present invention, air laid, air throughbonded nonwoven have been made by the applicant on a airlaying andair-through bonding line, using eccentric, polyethylenesheath/polypropylene core bicomponent fibers with a permanentincorporated into the polyethylene resin produced by DANAKLON Denmark,under the designation ESEWA, having a coarseness of 6.7 dTex. The web isdisclosed in more detail in WO Patent 94/28838 assigned to Palumbo, thefibers used in EP 0 340 763 assigned to Hansen.

The comparative example is an apertured formed film, such as supplied byTREDEGAR under the designation X5790 as referred to in the abovementioned patent U.S. Pat. No. 5,342,338.

TABLE 1 Comparative Test material example Basis weight [gsm] 60.0 62.2caliper (@ 552 Pa) [mm] 2.66 1.69 density (@ 552 Pa) [g/cm] 0.023 0.037caliper loss at max press. [%] 52.2 35.9 after cycle [%] 19.4 18.4 totaltest fluid pickup [g] 10.0 6.0 stain size [cm²] 44.4 54.7 materialcapacity [g/g] 37.5 17.6 material basis capacity [g/cm²] 0.23 0.11

As can be clearly seen, the test materials provide significantlyimproved medium viscosity storage capacity, and also a much increasedbasis capacity.

Absorbent Article

Without wishing to be bound by the theory, it is believed, that when thefeces is immobilized in the storage material, it does not return to soilor irritate the skin of the wearer. Furthermore, the low viscosity fecescan be dewatered by the capillary action of the fluid handlingcomponents.

While a high capacity as such is preferred for optimized material usage,high basis capacities are preferred to allow more freedom when designingarticles with improved fit (e.g. smaller articles), or improved urinehandling capability which might be interfering with the feces storage.

Hence, absorbent articles comprising the feces storage materialsaccording to the invention can be designed by simply inserting the fecesstorage material between the absorbent core 28 and the topsheet 24.Thereby, the amount (basis weight) and size of the feces storagematerial can be readily adjusted according to the needs of the intendedwearer group. Thus, when for example designing an article for an amountof feces of 100 g, about 3 g of the above exemplified material arerequired, or about 500 cm², or a patch of about 33 cm length and 15 cmwidth would be required. Such a patch would cover essentially the totalabsorbent core for example in baby diapers of a conventional MAXI size.Such a design is indicated in FIGS. 1 to 3 in the respective parts “a”.

An even preferred design is indicated in the “b” parts of the respectivedrawings, where by increasing the basis weight of the feces storagematerial the required size is significantly reduced. Then the fecesstorage materials can be advantageously be positioned in the rear partof the absorbent article, such that it is in registry with the analopening, extending even further towards the back of the absorbentarticle.

In case the resulting thickness of the total structure exceedsacceptable values, the absorbent core 28 can be designed such that it isthinner or spared out in the region of the feces storage material.

In particular in such designs, it might further be advantageous tofurther exploit the capillary action and optimize it further. Onespecific aspect of the present invention is the to create channels inthe feces storage material. Such channels can be achieved byconventional tools such as by removing material by cutting or scarfing.In this instance, the channels are defined by adjacent regions withrespectively different material thicknesses or basis weights. Or, suchchannels can be created by densification (embossing) in certain areas ofthe fecal storage material. Then such channels are defined by adjacentregions of different densities. Alternatively, the channels can haveboth differences in thickness and basis weight and density altogether.

More preferably, such channels can be created by using a methoddescribed in more detail in European patent application 96108394.6,filed on May 28, 1996, describing a suitable material and a preferredexecution for making such a material by a post formation treatment for aporous web by using two grooved rolls which are operated with such closetolerances, that the pores of the web are permanently deformed to acertain degree, thereby enhancing fluid transport properties.

With such structures it can be accomplished, that the dischargedfeces—or at least a part of these—can be distributed towards the rearpart of the article.

What is claimed is:
 1. A disposable hygienic article, comprising: aliquid pervious first topsheet; a liquid impervious backsheet at leastpartially peripherally joined to said first topsheet; and a fecesstorage material for pick up of low to medium viscosity fecesintermediate said first topsheet and said backsheet; characterized inthat the feces storage material has a feces storage capacity of at least20 g/g, when tested according to the described medium viscosity fecesstorage capacity test.
 2. A disposable article according to claim 1,whereby said feces storage material having a feces storage capacity ofat least 35 g/g.
 3. A disposable article according to claim 1, wherebysaid feces storage material comprises a fibrous structure.
 4. Adisposable article according to claim 3, whereby said fibrous structurehas not more than 55% caliper loss when submitted to the describedresiliency test.
 5. A disposable article according to claim 3, wherebysaid fibrous structure comprises channels in form of regions withdifferent thicknesses or densities.
 6. A disposable article according toclaim 4, whereby the feces storage material is treated by the steps offeeding a web having fluid distribution properties between a pair ofopposed pressure applicators comprising three-dimensional surfaces whichare complementary to one another, and subjecting the portions of saidweb located between said opposed pressure applicators to incrementalcross dimensional elongation by causing said opposed three-dimensionalsurfaces of said pressure applicators mesh with one another, wherebysaid web is at least partially permanently deformed.
 7. A disposableabsorbent article accoring to claim 1 wherein said first topsheet andsaid feces storage material are joined together essentially throughouttheir juxtaposed surface.
 8. A disposable absorbent article according toclaim 1, whereby the feces storage material is located only in the rearpart of said absorbent article.
 9. A disposable absorbent articleaccording to claim 1, further comprising an absorbent core intermediatesaid feces storage material and said backsheet.